Chloroquine

Chloroquine phosphate is in a class of drugs called antimalarials and amebicides. It is used to prevent and treat malaria. It is also used to treat amebiasis.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

• Aralen^®

Chloroquine is a prescription medication used to prevent and treat malaria. It is also used to treat amebiasis (an infection caused by the parasite Entamoeba histolytica). This medication belongs to a group of drugs called antimalarials and amebicides. The exact way it works to kill parasites is unknown.

Chloroquine comes in tablet form. Take this medication with food to minimize stomach upset. Chloroquine is taken once or twice a day. If used for the prevention of malaria, it is taken once a week beginning 2 weeks prior to traveling to an area where malaria is common.

Common side effects include headache, loss of appetite, diarrhea, and upset stomach.

Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.

Chloroquine is sometimes given only once per week. Choose the same day each week to take this medication if you are on a weekly dosing schedule.

To prevent malaria: Start taking the medicine 2 weeks before entering an area where malaria is common. Continue taking the medicine regularly during your stay and for at least 8 weeks after you leave the area.

Take chloroquine for the entire length of time prescribed by your doctor. If you are taking this medicine to treat malaria, your symptoms may get better before the infection is completely treated.

Use chloroquine regularly to best prevent malaria. If you stop using the medication early for any reason, talk to your doctor about other forms of malaria prevention.

In addition to taking chloroquine, use protective clothing, insect repellents, and mosquito netting around your bed to further prevent mosquito bites that could cause malaria.

If you use this medication long-term, your blood will need to be tested often. You may also need eye exams, and your doctor may need to check your knee and ankle reflexes. Visit your doctor regularly.

No medication is 100% effective in treating or preventing malaria. For best results, keep using the medication as directed.

Contact your doctor as soon as possible if you have been exposed to malaria, or if you have fever or other symptoms of illness during or after a stay in an area where malaria is common.

Store at room temperature away from moisture and heat.

For all uses of chloroquine:

• Tell all of your health care providers that you take chloroquine. This includes your doctors, nurses, pharmacists, and dentists.
• A very bad eye problem has happened with this medicine. This may lead to long-lasting eyesight damage. The risk may be higher in older people if chloroquine is used for a long time or if a higher dose of this medicine is used. Talk with the doctor.
• Have an eye exam as you have been told by your doctor.
• Be careful if you have G6PD deficiency. Anemia may happen.
• Have your blood work checked if you are on chloroquine for a long time. Talk with your doctor.
• Talk with your doctor before you drink alcohol.
• Some other drugs may need to be taken at some other time than this medicine. If you take other drugs, check with your doctor or pharmacist to see if you need to take them at some other time than chloroquine.
• If you are taking cyclosporine, talk with your doctor. You may need to have your blood work checked more closely while you are taking it with this medicine.
• This medicine may make you sunburn more easily. Use care if you will be in the sun. Tell your doctor if you sunburn easily while taking this drug.
• Low blood sugar has happened with chloroquine. Sometimes, this has been very bad and could be life-threatening. Talk with the doctor.
• Check your blood sugar as you have been told by your doctor.
• A very bad and sometimes deadly reaction has happened with this medicine. Most of the time, this reaction has signs like fever, rash, or swollen glands with problems in body organs like the liver, kidney, blood, heart, muscles and joints, or lungs. Talk with the doctor.
• Keep away from children. Accidental exposure may cause death. If a child takes chloroquine by accident, get medical help right away.
• If you are 65 or older, use this medicine with care. You could have more side effects.
• Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using chloroquine while you are pregnant.

Preventing malaria:

• Other measures are needed along with this medicine including using screens, bed netting, insect repellent (10% to 35% DEET), and permethrin spray on clothing and nets. Avoid spraying most insect repellents on children. Lower evening and night-time outdoor activity.
• If you are a pregnant woman and traveling to a malaria infested place, talk to your doctor about the risks first.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

For all uses of chloroquine:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
• Signs of low blood sugar like dizziness, headache, feeling sleepy, feeling weak, shaking, a fast heartbeat, confusion, hunger, or sweating.
• Change in eyesight, eye pain, or very bad eye irritation.
• Trouble controlling body movements.
• Restlessness.
• Seizures.
• Mood changes.
• Change in how you act.
• Not able to sleep.
• Feeling confused.
• Hallucinations (seeing or hearing things that are not there).
• Change in hearing.
• Ringing in ears.
• Muscle pain or weakness.
• A burning, numbness, or tingling feeling that is not normal.
• Fever or chills.
• Sore throat.
• Any unexplained bruising or bleeding.
• Feeling very tired or weak.
• A very bad skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis) may happen. It can cause very bad health problems that may not go away, and sometimes death. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.
• Heart problems like heart failure and certain very bad abnormal heartbeats have happened with this medicine. Sometimes, these heart problems have been deadly. Call your doctor right away if you have a fast or abnormal heartbeat; very bad dizziness or passing out; or shortness of breath, a big weight gain, or swelling in the arms or legs.

Preventing malaria:

• Fever that happens while in or after coming back from the malaria area.

Chloroquine is rapidly and almost completely absorbed from the gastrointestinal tract, and only a small proportion of the administered dose is found in the stools. Approximately 55% of the drug in the plasma is bound to nondiffusible plasma constituents. Excretion of Chloroquine is quite slow, but is increased by acidification of the urine. Chloroquine is deposited in the tissues in considerable amounts. In animals, from 200 to 700 times the plasma concentration may be found in the liver, spleen, kidney, and lung; leukocytes also concentrate the drug. The brain and spinal cord, in contrast, contain only 10 to 30 times the amount present in plasma.

Chloroquine undergoes appreciable degradation in the body. The main metabolite is desethylChloroquine, which accounts for one fourth of the total material appearing in the urine; bisdesethylChloroquine, a carboxylic acid derivative, and other metabolic products as yet uncharacterized are found in small amounts. Slightly more than half of the urinary drug products can be accounted for as unchanged Chloroquine.

Microbiology

Mechanism of Action
Chloroquine is an antimalarial agent. While the drug can inhibit certain enzymes, its effect is believed to result, at least in part, from its interaction with DNA. However, the mechanism of plasmodicidal action of Chloroquine is not completely certain.

Activity in vitro and in vivo

Chloroquine is active against the erythrocytic forms of Plasmodium vivax. Plasmodium malariae, and susceptible strains of Plasmodium falciparum (but not the gametocytes of P. falciparum). It is not effective against exoerythrocytic forms of the parasite.

In vitro studies with trophozoites of Entamoeba histolytica have demonstrated that Chloroquine also possesses amebicidal activity comparable to that of emetine.

Drug Resistance

Resistance of Plasmodium falciparum to Chloroquine is widespread and cases of Plasmodium vivax resistance have been reported.

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Tablet, Oral, as phosphate:

Aralen: 500 mg [equivalent to chloroquine base 300 mg] [DSC]

Generic: 250 mg [equivalent to chloroquine base 150 mg], 500 mg [equivalent to chloroquine base 300 mg]

Discoid lupus erythematosus

Data from a prospective, randomized, controlled, double-blind clinical trial supports the use of chloroquine in the treatment of discoid lupus erythematosus [Bezerra 2005]. Chloroquine also demonstrated a reduction in epidermal vascular endothelial growth factor (VEGF) experession resulting in a significant reduction in the median number of CD34+ dermal blood vessels [Lesiak 2009]. Additional data may be necessary to further define the role of chloroquine in the treatment of this condition.

There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.

Store at 25°C (77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F); protect from light.

Consult your pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.